This invention relates to the art of electrical circuit component manufacture and, more particularly, to improved means, including both the article and method for anchoring terminal leads or pins to a substrate and a circuit component supported by the substrate.
The increasing need for miniaturization of electrical components and the forming of electronic packages thereof, has called for a need for suitable substrates or bases upon which the components and circuits may be disposed. This in turn has required care in the selection of terminals and leads for mechanically interconnecting the components and circuits. It is often highly desirable to provide substrates of ceramic or glass or other frangible insulating materials for supporting the electrical circuitry. The circuitry may take the form of so-called "cermet" or thick film, or thin metallic or carbonaceous film materials disposed upon a substrate capable of being fired to join the film with the substrate.
Typically, terminal leads have been attached to a substrate to provide an electrical connection with a resistive or conductive film deposited on the substrate by means of soldering, mechanical crimping to the film and substrate with or without additional soldering, or by force fitting the lead into cavities formed in the substrate.
The field of the present invention is directed to attachment of leads, and particularly those of the pin type, to a substrate by swaging or other upsetting means directed to applying axial force to a lead member to provide laterally extending flange-like portions at the opposite ends of a through aperture in a substrate in combination with the resultant "bulging" of the portion of the lead member residing in the aperture to provide a secure anchor. Examples of prior art devices directed to this general method of attaching leads may be found in U.S. Pat. No. 3,257,708 granted to Alfred A. Stricker on June 28, 1966; U.S. Pat. No. 3,281,923 granted to Howard S. Best et al on Nov. 1, 1966; U.S. Pat. No. 3,659,245 granted to Robert L. Payne on Apr. 25, 1972 and U.S. Pat. No. 3,768,134 granted to Anthony F. Reda et al on Oct. 30, 1973.
Upsetting or swaging of terminal pins anchored in ceramic or glass based substrates have often resulted in a substantial "scrap rate" caused by substrate breakage during the terminal deformation operation. If the swaging force is too heavy, the substrate will crack; if the force is too light, the metal deformation will be incomplete and the connection will not function properly. Elaborate means of control have been provided in the past and, even then, there have been large quantities of nonrecoverable scrap made. In miniature electronic devices, the size of the substrate must be kept to a minimum -- a requirement that limits the stress-bearing cross section of the substrate. Successful swaging therefore requires that the component parts be specifically designed for stress-bearing efficiency.